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Max
11-07-2003, 09:38 AM
What is the optimum resolution for a stepper driven axis?
In other words, turns per inch.

I have a stepper driven screw drive that is 1 revolution per inch.
Is that resolution good enough or should I plan on gearing it down with a pulley/belt ?

Also ... I'm working on another project that is toothed belt driven on a 48" axis.
What is the optimum stepper turns per inch that I should shoot for?

I will be cutting and engraving wood and foam not machining mill parts, if that makes a difference.

balsaman
11-07-2003, 12:17 PM
1 turn per inch is not too handy. 5 turns per inch on a standard 200 step stepper gives you .001" resolution. That's a good goal. For small steppers (~100 oz.) which will probably turn a little faster 10 turns per inch is a good bet.

Eric

ViperTX
08-31-2004, 03:36 PM
If your steppers are Not directly coupled to your axis then you must also take into account the gear ratio of the drive mechanism to determine actual resolution.

jcc3inc
09-04-2004, 12:07 PM
Dear Sir:
You might consider microstepping. Although the increments are not precise divisions of the basic step, the system operates MUCH more smoothly. I use 10x microstepping with 2" circumference pinions, resulting in .001"/step. In your case, 10x microstepping would give you .0005"/step. (200 x 10 steps). I like direct coupling if the numbers (torque, speed, etc) come out right. My stepper drivers are Gecko Systems, and I am quite happy with them.
Regards,
Jack C.

Graham S
09-04-2004, 05:57 PM
With the typical stepper motor (400 steps, half stepped) you would get 1/400 = 0.0025" resolution or 24.4/400 = 0.0635mm resolution. So ask yourself is that enough for what you want to make?

With a 1" lead the leadscrew will give you less force for a given torque, for that reason you might want to add a little gearing or go for the proven 5 TPI screws.

See the FAQ section, there is now a good description of those things by Arvid.

Graham

tachus42
09-05-2004, 04:06 AM
Micro stepping will only give you enhanced resolution if you motors have much more torque than required, which is unlikely with a 1 tpi lead screw. At their rated torque stepper motors will be lagging 1/2 a full step from the commanded position. Microstepping will of course give you much smoother motion.